Automatic magnification control for projector



FIPBZIZ XR 2,747,456

May 29, 1956 F. WALLER ETAL 2,74?,4 56

' AUTOMATIC MAGNIFICATION CONTROL FOR PROJECTOR Original Filed Dec. 14, 1946 4 Shuts-Shoot 1 FlG.l.

ATTORNEYS May 29, 1956 F. WALLER EI'AL 2,747,456

AUTOMATIC IMGNIFICATION CONTROL FOR PROJECTOR Original Filed Dec 14, 1946 4 shoots shoet 2 Flea.

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AUTOMATIC NAGNIFICATION comm. FOR PROJECTOR Original Filed Dec. 14, 1946 4 Shuts-Shut a B2 28 w 44/ I42 #4 INVENTORS "(M Wm M ALI'TORNEYS May 29, 1956 F. WALLER ETAL 2,747,456

Au'rolmxc MAGNIFICATION comaox. FOR PROJECTOR Original Filed Dec. 14, 1946 4 Shoots-Shoot. 4

MAGNIFICA TIOV CON TQOL MOTOR VERTICAL CSZT ZOL 4o MOTOR TRA NSVEPSE 5H IF T CON TQOL MOTOR BY Av United States Patent Ofiice AUTOMATIC MAGNIFICATION CONTROL FOR PROJECTOR Original application December 14, 1946, Serial No. 716,344. Divided and this application April 6, 1981, Serial No. 219,597

6 Claims. (CI. 33-17) This invention relates to motion picture projection and the invention is intended primarily for controlling the projection where several images 'are thrown on contiguous areas of the same screen. in such cases it is essential that the different images be located with great exactness since the composite images are seriously impaired if' any one of the individual images overlaps an adjacent image or does not completely fill its intended area of the screen.

When a number of images are projected on a single large screen for the purpose of producing a composite picture, it is usual to employ ditferentprojectors for projecting the respective images. Experience has shown that it is not sufiicient to merely adjust the apparatus initially forthe correct correlation and magnification of the images from the different projectors, because the film is not entirely uniform. The location of the image on the film sometimes varies along the length of the film, and the actual dimensions of the film vary at times from shrinkage and other causes that make both-the image location and magnification vary.

in its broadest aspects it is an object of this invention -to provide improved projection apparatus for motion picture film, and especially for the projection of the indi- 'vidual images used to make up larger composite images on screens of large area.

Another object of the invention is to provide apparatus for controlling the sire of the image on the screen, that is, the area of the screen that is illuminated by the image of the film frame area at the film gate of the projector. This is done by controlling the magnification of the film image so that the image can be made to-lill a predetermined area of the screen regardless of variations in the actual dimensions of the picture area of each film frame, and even though the picture area of the film sometimes becomes'less than the open area of the film gate.

It is another object of the invention to provide such magnification control by automatic means which are controlled by light-sensitive devices located in the path 'of a portion of the-light from the projector. in accordance with another feature of the invention, this automaticma'gnification control is combined with image location control devices which maintained images in proper relation for matching of those images which are adjacent to one another on the screen when projecting a mosaic picture.

The image location control without the magnificationcontrol is claimed in.our copending application Serial No. 716,344, tiled December 14, 1946, now Patent No.

2,563,892 of which this application is a division.

Other objects, features and advantages will appear or be pointed out as the specification proceeds.

in the drawings, forming a part hereof, in which like reference characters indicate corresponding parts inall the views.

Figure l is a diagrammatic view illustrating the application of the invention to the control of the location of an image on a single screen.

2,747,456 Patented May 29, 1958 Figure 2 is a detailed diagrammatic view showing the location of the photocells used in the combination illustrated in Figure 1.

Figure 3 is a diagrammatic view illustrating the applition of the invention to the control of both the location and magnification of a number of images projected from different films on a large-area screen to form a composite picture.

Figure4isanenlargeddetailedviewofoneotthe films used in Figure 3.

Figure 5 is a perspective, diagrammatic view of projection apparatus for controlling the location and magnification of the respective images projected in Figure 3.

Figures 6 to 9 are detail views of the compensating linkages used with the projection apparatus of Figure 5.

, Figure 10 is a wiring diagram showing the circuits by which the photocell controls operate the motors of the apparatus illustrated in Figure 5.

The apparatus for controlling image location only will be described first, and then the idea of the magnifies tion contro Figure 1 shows a motion picture film 14 which runs through projection apparatus having a guide 11 for the left hand edge of the film. One film frame 13 is lustrated, but it will be understood that the film has r. plw rality of successive frames. The film 10 has two light apertures 15 and 16 associated with each frame and located along the left hand marginofthefilm.

Light from a light source 12 passes through the film frame 13, and through the light apertures 15 and 16 to a lens 19 which projects the image of the rum frame on a screen 20. The light passing through the apertures 15 and 16 is focused by the lens I! on light responsive means 22' and 23 respectively. located along one side of the screen 20, and preferably embedded in a frame 25 that surrounds the screen 20.

The lens 19 is carried by a lens mount 21 which is movable vertically in guides 28. The lens mount 27 is moved up and down in the guides 21 by a pinion 29 meshing with a rack 30 secured to one edge of the lens mount 27. The pinion 29 is driven by reduction gearing 32 from an electric motor 33 mounted on a base 34.

i The base34 is supported by guides 36 and is slidable horizontally along the guides 36, such horizontal movement being in a direction transverse of the light beam by which the film is projected on the screen. The base 34 is connected with a rack 38 driven by a pinion 39 from an electric motor 40 through reduction gearing 41.

The electric motors 33 and 44 are reversible and their direction of movement is controlled by relays. The motor 33 is connected with relays 44 and 45. These relays are operated by separate photocells 41 and 48. respectively, of the light-responsive means 22.

When the image of the light aperture 15 strikes both of the photocells 47 and 48 with equal. intensity, both of the relays. 44 and 45 are closed and the motor 33 remains stationary. When the image of the light aperture 15 is high and concentrates illumination on the photocell 41, the relay 44 remains closed while the relay 45 opens and the motor 33 moves the lens mount 27 down until the photocells 47 and 42 are both illuminated substantially equally and the image is restored to its proper location. Downward movement of the image of the light aperture 15 so as to concentrate the illumination on the photocell 42 causes relay 44 to open while relay 45 remains closed and energizes the motor 33 to rotate in a direction to raise the lens mount 27 and restore theimage on the screen to the desired location.

The operation and direction of rotation of the motor 40 is controlled by relays 50 and 51 connected with photocells 52 and 53 respectively of the light-responsive means 23. "Shifting of the image of the light aperture them.

' amuse 16 so as to concentrate the illumination on only one of the photocells 52 and 53 causes one or the other of the relays 50 and 51 to open while the other remains closed and causes the motor 48 to operate to shift the base 34 and lens mount 27 in a direction to restore the image of the light aperture 16 to the desired location.

Figure 2 shows a construction in which the photocells 47 and 48 are located behind the frame 25 of the screen. A reflector 88 is located in line with an opening 56 in the frame 25, and this reflector hastwo reflecting surfaces that are set at an angle to the axis of the opening 56 so that one-half of the rays of light entering the opening 56 are reflected to the photocell 47 and the other half to the photocell 48. The reflecting surfaces are preferably curved to concentrate the light on the photocells 47 and 48.

In positioning the photocells, it is advantageous to have the long dimension of each photocell at right angles to the direction of movement which the photocell controls. For example, in Figure l, the photocells 47 and 48 which control the vertical movement of the image are positioned with their long dimensions extending horizont'ally. This orientation results in the most rapid change in illumination intensity for a given displacement of the control beam. Conversely, the photocells 52 and 53, which control horizontal movement of the image, are

screen area is illuminated by the images of a film 72 projected through a lens 73, and images on a film 74 are projected on the screen area 66 through a lens 75. The images on the screen area 64 and 6S meet along a line 77 and the image on the center area 64 meets the image on the right hand area 66 along a line 78.

In order to have the different images on the screen of Figure 3 appear as a single picture it is essential that the images from the respective projectors be not only correctly located both horizontally and vertically so as to meet exactly along the lines 77 and 78, but it is also essential that the images have the proper magnification so as to fill the intended areas of the screen. For example, if the film 70, or some portion of it, has shrunk so that the image of the film frame, as projected on the center section 64, is not quite wide enough to fill in the distance between the lines 77 and 78, then image locating apparatus, such as described in connection with Figure i. cannot make the image on the center section register with the images on the areas 68 and 66 at the same time.

This invention provides for automatic control of the magnification by light responsive means which cooperate with light apertures in the film. Such apparatus moves the projector lens toward or from the screen to change the magnification and at the same time provides a constant focus with a focus follow-up device similar to the focus control connections used on conventional enlargers.

Figure 4 shows the film 78 on an enlarged scale. This film has conventional apertures 88 for receiving the teeth of the film-driving sprockets of the projector, but the film frames 81 are spaced so as to leave margins between in these margins there are light apertures 83, 84 and 85. Two of these apertures, for example the aperturcs 84 and 88, are used to control the location of the image, in the manner described in connection with Figure l, and the remaining light aperture 83 is used to control the magnification of the image. The reason for having the light apertures 83, 84 and 85 in the margin between the film frames 81 is that it permits the light responsive devices, with which these light apertures cooperate, to be located in the frame of a screen used for composite pictures, as in Figure 3.

The light responsive means on which the images of the light apertures 83, 84 and are thrown are indicated in Figure 3 by the reference characters 87, 88 and 89 respectively. Similar light responsive means are located in the frame 68 under the screen areas 65 and 66.

Figure 5 is a diagrammatic showing of the projection apparatus used for projecting the film 70 in Figure 3. Similar projection apparatus is used for each of the films 72 and 74. Much of the apparatus shown in Figure 5 is the same as shown in Figure 1, and is designated by the same reference characters, but the motor and adjusting mechanism in the apparatus of Figure 5 are located on the opposite side of the lens from the structure shown in Figure 1.

The projection apparatus of Figure 5 includes, in addition to the structure already described in connection with Figure 1, a film gate 92 that serves as a mask for determining the limits or marginal edges of the image projected on the screen. The film gate 92 is supported in guides 93 carried by a slide 94 which is movable horizontally in guides 96. These guides 96 extend parallel to the guides 36; and the base 34 is connected with the slide 94 by a linkage which causes the slide 94 to move whenever the base 34 moves along its guides 36. The linkage connecting the base 34 and slide 94 will be described in connection with Figures 8 and 9, and for the present it is sufficient to understand that the slide 94 moves in the same direction as the base 34 but for a longer, and pro portional, distance which is so correlated with the movement of the base 34 that the edges of the projected image, as determined by the edges of the opening through film gate 92, remain in the same position on the screen in spite of horizontal movement of the lens 19.

The film gate 92 is movable vertically in the guides 93 and is supported by a link 98 connected by other links with the lens mount 27. This linkage, will be described in connection with Figures 6 and 7 and for the present it is sufficient to understand that vertical movement of the lens mount 27 in the guides 28 causes the film gate 92 to move up and down in the guides 93 in the same direction as the movement of the lens mount 27 but for a distance greater than the movement of the lens and so correlated with the movement of the lens that the edges of the projected image, as determined by the top and bottom edges of the film gate 92, are not influenced by the vertical movement of the lens 19.

'l11e entire projector mechanism and lens-adjusting apparatus is supported on a base 100 which slides in guides 181 toward and from the screen. A rack 103 is attached to the base 100 and meshes with a pinion 104 that is driven by a motor 105 for moving the base 100 along its guides 181. The movement of the base 180, along the guides 101 changes the magnification of the image. The lens 19 can be moved back and forth in the lens mount 27 by any suitable focus follow control mechanism for maintaining the focus of the image in spite of changes in the magnification. v

Figures 6 and 7 show the linkage between the film gate 92 and the lens mount 27. The film gate 92 has a yoke 108 at its upper end, and this yoke 108 is connected with the link 98 by a pin 109 extending through a slot 110 in the rearward end portion of the link 98.

The link 98 is supported from a bracket 112 by a fulcrum pin 113. At the forward end of the bracket 112 there is a yoke 115 with a pin 116 which serves as a fulcrum for another link 117. Motion of the link 117 is transmitted to the link 98 by a pin 120 which extends from one side of the link 117 into a slot 121 in the for ward end portion of the link 98.

The forward end of the link 117 is connected to the lens mount 27 by an intermediate link 123. This intermediate link is secured to the lens mount 2'! by a pivot connection 124 and the upper end of the intermediate link l23isconnectedwiththelink111byapln126extending through a slot 121 in the forward end of the link 117.

The lever arms of the link 117 are substantially equal, and the lever arms of the link 96 are so related that the ratio of the length of the forward arm to the length of the longer rearward arm of the link 98 is equal torthe ratio of the distance of the lens 19 from the screen to the distance between the film and the screen. it is not necessary that the link 11! have arms of equal length and it is sufficient that the leverage of the compound lever system which connects the lens mount with the film gate be so correlated with the distances between the lens and screen, and the film and the screen, that the edges of the image on the screen, as determined by the film gate, will be be moved as a result of movement of the lens Since the respective distances of the lens and the film from the screen do not remain in the same ratio for all operating conditions of the projector, it is preferable to have the leverage of the compound lever system adjustable. The bracket 112 is supported by a stand 126 which is rigidly secured to the-base 100. The bracket 112 is movable along the stand 128 as a guide toward and from the film gate 92 and lens mount 26. The bracket 112 is shifted by turning an adjusting screw 136.

The adjusting screw 136 is rotatable in a bearing 132 which is part of the stand 112. This screw is held against axial movement with respect to the bearing 132 by collars on thescrew. The forward end of the screw 13. threads through slug 134 to the bracket 112 for, moving the bracket along the stand 126. This movement of the bracket 112 does not distort connections between the leverage system and the film gate 92 and lens mount 21 because the pins 109 and 126 extend through slots. in the links 98 and 117. This forward or rearward adjustment of the bracket 112 does change the leverage of the system, however, since it changes the eflective lengths of the forward lever arm of link 117 and the rearward lever arm of link 98, and these changes are opposite to one another, that is, one lever arm gets shorter as the other gets longer, thus changing the leverage of the system.

Figures 8 and 9 show the linkage connecting the base 34 with the slide 94. A stud 140 extends up from the slide 94 and through a slot 141 in a link 142. This link 142 is movable sngularly in a horizontal plane about a fulcrum pin 144 secured to a bracket 145, and the links 142 and 147 are connected by a pin 150 secured to the link 147 and extending through a slot 151 in the upper link 142. The forward end of the link 14! is slotted and a pin 149 extends through this slot and connects the link with the base 34.

The bracket 145 is slidable in guides 153 on the base 100, and can be adjusted by a screw 155 extendingthrough a lug 156 which forms a part of the bracket 145. The screw 155 is held against axial displacement by collars on opposite sides of a lug 158 of the projector base 109.

Adjustment of the screw 155 in Figures 8 and 9 moves the bracket 145 and changes the leverage of the composite lever system by which the slide 94 is connected with the base 34.

Figure shows a wiring diagram for controlling the apparatus illustrated in Figure 5. Vertical movement of the lens mount for image location is controlled by photoelectric cells 47 and 48, and horizontal movement of the lens and its supporting structure for image location is controlled by photoelectric cells 52 and 53 as in the apparatus shown in Figure l. The third motor 105 for operating the magnification control is connected with relays 161 and 162 in the circuits of photocells 163 and 164 respectively. As in the case of the image control motors, the operation of which was described in detail in connection with Fig. l, the motor 105 does not run when light is supplied to both of the photocells 163 and 164 andtberelays161and162arebothclosed. Whenthe photocell 163 only receives light, the motor 195 is operated in one direction, and when the photocell 164 only receives light, the motor is operated in the opposite direction.

It will be understood that the film 16 in Figure l is used with a film gate, and that linkages such as shown in Figures 5 to 9 are employed for preventing movement of the edges of the illuminated field on the screen when the lens 19 is moved by the image locating controls.

With means provided for positioning one side edge of the image, the magnification control can be efiected by a single pair of photocells, as will be understood by referring to Figure 3. The image location controls move the lens so that the images of the light apertures 84 and I! register with the light responsive devices 68 and I9, and maintain the left-hand edge of the projected image even with the line 17. With the position of this line definitely located, the magnification of the image can be determined by the movement of the image of the light aperture 83.

in order for the magnification control by photocells 163 and 164 to operate, the framing of the picture must be approximately correct and the left-hand edge of the image must be accurately located. In the illustrated embodiment, therefore, the transverse shift control is a part of the magnification control. If this image falls to the right of the light responsive means 81 in Figure 3 the magnification is too great, and if it falls to the left of the light responsive means 61, the magnification is insufiicient. The magnification control circuit-shown in Figure 10 will operate the motor and adjust the magnification until the image of the light aperture 63 registers with the light responsive means 81.

The preferred embodiments of the invention which have been described obtain image location by moving the lens, but the invention can be modified to move the film, or the projector. Other changes and modifications can be made and some features of the invention can be used. without others.

We claim as our invention:

l. The combination with a motion picture projector having a lens and a film gate that serves as a mask for determining the edges of the image projected on a screen, of image location control apparatus including mechanism with light-responsive control means for automatically adjusting the lens horizontally to cause a horizontal shifting of the image on a screen in response to horizontal displacement of a control beam projected from the film, the projector including guide means on which the lens has axial movement, other mechanism -with light-responsive control means for automatically adjusting the lens axially to cause enlargement or reduction of the size of the image on the screen in response to horizontal displacement of another control beam projected from the film, and compensating connections between the lens and the film gate for moving the film gate in such a correlation with the lens movement that the margins of the image on the screen, as determined by the film gate, remain unchanged with respect to the screen for diiferent horizontal adjustments of the lens.

2. Motion picture projection apparatus including, in combination, a guide along which a film is moved with intermittent motion. a lens through which an image of the film is projected on a screen. means for giving the lens components of movement both vertically and horizontally in directions transverse of the axis of the lens and substantially horizontally in the direction of the axis of the lens. said means including a lens support, guideways in which the lens support is movable in the direction of one of said components, a carriage by which the guideways are sup ported, other guideways on which the carriage is movable in the direction of another of said components, a second carriage on which said other guideways are supported. additional guideways on which said other carriage is movable in the direction of the third component, a motor ans-mes for moving the lens support along said guidewayr, another motor for moving the carriage along said other guideways, a third motor for moving the second carriage along said additional guideways, automatic control means for all three of the motors including light-sensitive devices that are in the path of light projected through control apertures of the film for operating the motors to maintain images of the control apertures in definite locations and thus maintain the image of the film in a definite location on the screen and with the image filling a predetermined area of a desired size on the screen.

3. Motion picture projection apparatus including, in combination, a guide along which a film is moved with intermittent motion, a lens through which an image of the film is projected on a screen, means for giving the lens components of movement both horizontally in directions transverse oi the axis of the lens and substantially horizontally in the direction of the axis of the lens, said means including a lens support, guideways in which the lens support is movable in the direction of one of said components, a carriage by which the guideways are supported, other guideways on which the carriage is movable in the direction of the other of said components, a motor for moving the lens support along the guideways, another motor for moving the carriage along said other guideways, automatic control means for both of the motors including light-sensitive devices that are in the path of light projected through control apertures of the film for operating the motors to maintain images of the control apertures in definite locations and thus maintain the image of the film in a definite horizontal location on the screen and with the image filling a predetermined area of a desired size on the screen.

4. Motion picture projection apparatus for projecting an image that constitutes an area of a mosaic picture on a screen with at least one edge of the image abutting another area of the mosaic picture, said apparatus including a projector comprising a film gate, a lens mount, apparstus for advancing a film, mechanism that moves a-portron of the projector in directions that change the location i the projected image area horizontally onthe screen, other mechanism for moving a portion of the projector in axial directions to change the magnification of the image area to adjust the size of said image to fill a desired area of the screen, and separate control means for the respective mechanisms, said control means including lightresponsive devices located in front of the projector in the path of light projected through the film.

5. The motion picture projection apparatus described in claim 4 and including mechanism that moves a portion of the projector in vertical directions to change the location of the projected image area vertically on the screen, and control means for the vertical change mechanism including light-responsive devices located in front of the projector in the path of light projected through the film.

6. Apparatus for projecting an image that is to constitute an area of a mosaic picture on a screen, which area abuts with another area along at least one edge of the image, said apparatus including a projector comprising parts through which a light beam passes between the film and the screen, said parts including a film gate and including also a lens mount that is movable transversely and axially oi the light beam, apparatus for advancing a film, mechanism that moves the lens mount with respect toboththefilmandfilmgateandacrossthclightbeam transversely, motor means for operating said mechanism, other mechanism that moves at least part of the projector axiallywithrespecttothescrecntochangcthesizeofthe image on the screen, other motor means for operating said other mechanism, and automatic controls for both or the motor means including light sensitive devices located in front oftheprojector andinthepathofaportionoi the light beam that is projected through the film.

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